Taking into account the implicit/explicit knowledge of Tense Consistency (TC), this study aimed to investigate TC observance across Iranian EFL learners' proficiency specifically at elementary, intermediate and advanced levels. To achieve this, the Oxford Placement Test, Gap Filling Task and Spoken Performance Task were administered to 154 learners. The goals were to categorize the participants into three proficiency levels, assess their explicit TC knowledge, and to evaluate their implicit TC knowledge respectively. The results endorsed the linearity of the explicit utilization of TC across proficiency groups; however, the implicit use of TC was demonstrated to be nonlinear, with the elementary learners outperforming the intermediate ones. Accordingly, the researchers suggested the introduction of a new term "tick-shaped improvement".